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/* Copyright (c) 1992 Regents of the University of California */ |
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/* Copyright (c) 1993 Regents of the University of California */ |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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static int CLRCUBE[3][2] = {0,NRED,0,NGRN,0,NBLU}; |
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/* maximum propagated error during dithering */ |
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#define MAXERR 20 |
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/* define CLOSEST to get closest colors */ |
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#ifndef CLOSEST |
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#ifdef SPEED |
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#if SPEED > 8 |
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#define CLOSEST 1 /* this step takes a little longer */ |
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#endif |
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#endif |
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#endif |
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new_histo() /* clear our histogram */ |
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ncolors = 256; |
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/* partition color space */ |
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cut(CLRCUBE, 0, ncolors); |
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#ifdef CLOSEST |
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closest(ncolors); /* ensure colors picked are closest */ |
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#endif |
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/* return new color table size */ |
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return(ncolors); |
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} |
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int p; |
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register int box[3][2]; |
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{ |
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long sum[3]; |
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int r, g, n; |
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register int b, c; |
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unsigned long sum[3]; |
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unsigned r, g, n; |
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register unsigned b, c; |
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/* sum pixels in box */ |
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n = 0; |
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sum[RED] = sum[GRN] = sum[BLU] = 0; |
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} |
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histo[r][g][b] = p; /* assign pixel */ |
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} |
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if (n >= (1<<23)/HMAX) { /* avoid overflow */ |
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sum[RED] /= n; |
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sum[GRN] /= n; |
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sum[BLU] /= n; |
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n = 1; |
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} |
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if (n) { /* compute average */ |
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clrtab[p][RED] = sum[RED]*256/NRED/n; |
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clrtab[p][GRN] = sum[GRN]*256/NGRN/n; |
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clrtab[p][BLU] = (box[BLU][0]+box[BLU][1])*256/NBLU/2; |
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} |
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} |
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|
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#ifdef CLOSEST |
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#define NBSIZ 32 |
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static |
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closest(n) /* make sure we have the closest colors */ |
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int n; |
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{ |
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BYTE *neigh[256]; |
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register int r, g, b; |
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#define i r |
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/* get space for neighbor lists */ |
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for (i = 0; i < n; i++) { |
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if ((neigh[i] = (BYTE *)malloc(NBSIZ)) == NULL) { |
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while (i--) |
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free(neigh[i]); |
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return; /* ENOMEM -- abandon effort */ |
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} |
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neigh[i][0] = i; /* identity is terminator */ |
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} |
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/* make neighbor lists */ |
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for (r = 0; r < NRED; r++) |
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for (g = 0; g < NGRN; g++) |
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for (b = 0; b < NBLU; b++) { |
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if (r < NRED-1 && histo[r][g][b] != histo[r+1][g][b]) |
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addneigh(neigh, histo[r][g][b], histo[r+1][g][b]); |
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if (g < NGRN-1 && histo[r][g][b] != histo[r][g+1][b]) |
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addneigh(neigh, histo[r][g][b], histo[r][g+1][b]); |
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if (b < NBLU-1 && histo[r][g][b] != histo[r][g][b+1]) |
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addneigh(neigh, histo[r][g][b], histo[r][g][b+1]); |
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} |
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/* assign closest values */ |
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for (r = 0; r < NRED; r++) |
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for (g = 0; g < NGRN; g++) |
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for (b = 0; b < NBLU; b++) |
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setclosest(neigh, r, g, b); |
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/* free neighbor lists */ |
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for (i = 0; i < n; i++) |
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free(neigh[i]); |
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#undef i |
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} |
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|
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|
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static |
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addneigh(nl, i, j) /* i and j are neighbors; add them to list */ |
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register BYTE *nl[]; |
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register int i; |
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int j; |
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{ |
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int nc; |
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char *nnl; |
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register int t; |
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for (nc = 0; nc < 2; nc++) { /* do both neighbors */ |
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for (t = 0; nl[i][t] != i; t++) |
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if (nl[i][t] == j) |
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break; /* in list already */ |
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if (nl[i][t] == i) { /* add to list */ |
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nl[i][t++] = j; |
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if (t % NBSIZ == 0) { /* enlarge list */ |
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if ((nnl = realloc(nl[i], t+NBSIZ)) == NULL) |
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t--; |
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else |
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nl[i] = (BYTE *)nnl; |
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} |
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nl[i][t] = i; /* terminator */ |
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} |
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t = i; i = j; j = t; /* swap and do it again */ |
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} |
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} |
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|
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|
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static unsigned |
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dist(col, r, g, b) /* find distance from clrtab entry to r,g,b */ |
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register BYTE col[3]; |
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int r, g, b; |
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{ |
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register int tmp; |
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register unsigned sum; |
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tmp = col[RED]*NRED/256 - r; |
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sum = tmp*tmp; |
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tmp = col[GRN]*NGRN/256 - g; |
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sum += tmp*tmp; |
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tmp = col[BLU]*NBLU/256 - b; |
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sum += tmp*tmp; |
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return(sum); |
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} |
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|
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|
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static |
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setclosest(nl, r, g, b) /* find index closest to color and assign */ |
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BYTE *nl[]; |
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int r, g, b; |
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{ |
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int ident; |
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unsigned min; |
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register unsigned d; |
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register BYTE *p; |
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/* get starting value */ |
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min = dist(clrtab[ident=histo[r][g][b]], r, g, b); |
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/* find minimum */ |
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for (p = nl[ident]; *p != ident; p++) |
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if ((d = dist(clrtab[*p], r, g, b)) < min) { |
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min = d; |
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histo[r][g][b] = *p; |
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} |
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} |
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#endif |